Electric heater



Patented Mar. 6, 1928.

UNITEDl STATESv PATENT OFFICE.

WILLIS N. VANATTA, OF ONTARIO, CALIFORNIA, ASSIGNOR TO EDISON ELECTRICAPPLIANCE COMPANY. INC., OF CHICAGO, ILLINOIS, A CORPORATION OF NEWYORK.

ELECTRIC HEATER.

Application led December 29, 1924. Serial No. 758,501.

My invention relates to electric heaters and has for its object theprovision of simple and reliable means for protecting electrlc heatersfrom overheating.

More specifically my invention relates to temperature cut-outs forelectrically heated devices whereby the electric heating circuit isopened upon the occurrence of a redetermine maximum temperature. yinvention has particular application to electric flat-irons although itobviously has other uses.

In carrying out my invention I p rovide a ratchet wheel for holding thecircuit control means in closed circuit position and se# cure theratchet wheel against rotation by means of" a stem, one end of whichextends through an off-center aperture in the ratchet wheel, the otherjend being secured by a fusible metal.

, For a more complete understanding of my invention, reference should behad to the accompanying drawing in which Fig. 1 is an elevation viewpartially in section of an electric flat-iron embodying my invention;Fig. 2 is an enlarged plan view of the switching mechanism showing theswitch in closed position; while Fig. 3 is an enlarged frag- Amentaryview in section showing the anchoring means for the switch holdingmember.

Referring to the drawing, I havefshown my invention in one form asapplied to a well known type of r flat-iron comprising a sole plate 10and a pressureplate 11 between which is clampeda suitable electricresistance heating unit 12. As shown, the

' plates are secured together by means of a screw 13. In the sole plateis a circular recess 14 in which is secured a sealed receptacle 15containing a suitable fusible metal or alloy 16. The receptacle 15 is.made of suitable material such assteel andl has its surface oxidized orotherwise treated or protected to prevent au'ialgamation at hightemperature with the fusible metal, for example when the fusible metalis in a molten condition.

Extending upward from the receptacle 15,

through a tapered circular opening 17 in the pressure plate, is a stemor switch holding member 18. This stem has a portion 19 of reduced sizeat its upper end, which portion4 extends through a suitable off-centeraperstem 18 which is ble metal, and

ture in a horizontally disposed ratchet wheel 2O cooperating with theswitching mechanism in the circuit of the heating unit 12. The lower endof the stem 18 extends into the receptacle 15 and is normally secured bythe fusible metal. When so secured the stem secures the ratchet wheelagainst turning and thereby holds the switching mechanism in closedcircuit position. Upon the occurrence of an excessive temperatureresulting in fusing of the alloy metal, the stem is freed and can swingaround to allow an appreciable rotation of the ratchet wheel whereby theswitching mechanism is released and the heating circuit opened.

Any suitable switching mechanism may be used in the circuit of theheating unit 12. The particular switching mechanism shown is describedand claimed in United States Patent No. 1,439,979 to Earl H. Richardson,dated December 26, 1922, and therefore will not be described in detail.

The ratchet wheel 20 is secured to the lower end of a shaft 21. Thisshaft is ro tatably mounted in a vertical position on brackets 22 and 23formed by striking upward and suitably shaping the end of a metallicsupporting plate 24, which is secured on the top of the pressure plate11. The shaft may be upheld by means of a washer' 24 secured on itsupper end resting on bracket 22, and revented from sliding upwards bymeans og) a shoulder on its lower end engaging the lower side of thebracket 23. An aperture 25 is provided in, the bracket 23 through whichthe ratchet wheel projects toward the left hand,'as viewed in Fig. 2.The ratchet is prevented from rotating in a Clockwise direction, asviewed in Fig. 2, bymeans of a spring arm 26 secured at one end to thebracket 23 and having its free end in engagement with the teeth of theratchet.

Rotation of the ratchet in a counter-clockwise direction is preventednormally by the in turn secured by the fusithus holds the switchingmechanism in closed circuit position against the force exerted by acomparatively strong spiral spring 27. This spring has one end 28adjustably secured to the supporting plate 24 while its other end is oeratively connected through a link 29, yo e- 30, and link 31 titllsuitable knife edge bearings 33.

to the movable end of a switch arm 32. 'llhe other end ot' the switcharm is pivoted on 'lhe yoke member' 30 is pivoted centrally on a loop onone end of an operating arm 3l, the other end of whichris provided withknife edge bearings 35 on which the member 34 is pirated. It right angleentension 34 is provided ou the member 34C and on this exteiision is aspring latch 36 which cooperates with the teeth ot' the ratchet wheel2() to secure the member 34.- iu closed circuit position against' thetorce exerted by spring 27 The action ot' the spring 27 is in suchdirection as to tend to throw the ratchet wheel in a countersclockwisedirection about its pivot and thus move the bridging circuit closingmember 37 away from the stationary contacts 38 and 39 to open theheating circuit. As long as the ratchet wheel is secured by the fusiblemetal, as shown in llig. 2, the switch is maintained closed by thecngagement of the latch 3G therewith. lln case ot excessivetemperatures, however, sutlicient to l'usc the metal 16, the stem 18will be released allowing the ratchet wheel to rotate in acounterclock\vise direction, uuder the intluence of the torce applied bythe spring 27, until latch 36 slips ott the ratchet wheel whereupon theswitch is lopened by the spring 27. After the stem 18 has been againsecured by the soliditication of the usible metal, the heating circuitmay be closed by pressing inward on a button 40 which is pivotallyattached to the operating member 34. The spring arm 26 prevents backingup of the ratchet wheel, due to any loosening of the parts, when theswitch is being closed.

As shown in lFig. 3, the receptacle 15 for the fusible metal is providedwith a cover 41 which is a flexible diaphragm made of a suitable metal,such as manganese nickel. 'llhe receptacle 15 has a flanged top uponwhich the cover' or diaphragm 4l rests, a clamping ring 42 being placedon the diaphragm and the container sealed by means ot a brazed or weldedjoint 13 between the tlanged edgeI of the receptacle, the diaphragm andthe clamping ring. 'lhe stem 18 is carried by the diaphragm L tl andextends centrally through it into the receptacle. A. suitable anchormember la is preterably provided on the lower end ot' the stem. rlhisanchor may consist of two prongs 45 and 4G which are embedded in thefusible metal 1G and thoroughly secure the stem. rlhe-stem is tightlysecured to the diaphragm in this central position by means ot` a brazedor welded lioint a7. lt will be observed that the. receptacle 15 is thussealed so that the fusible metal 16 is protected against oxidation.VVhenvthe metal fuses, releasing the lower end of the Stem, thediaphragm lexes so as to permit the stem to swing about its point oitsupport on the diaphragm and in edect provides a universal joint orpivot tor the stem The axis of the shaft 21 passes through the point ofsupport oit stem 18 on the diascribe a portion ot a cone, this movementbeing continued upon each release and the upper end ot' thestemdescribing a small circle.

For the purpose oit preventing the fusible metal from coming inv contactwith the diaphragm t1, a disc 48 is secured to the stem 18 at its lowerend just above the anchor member et. lmmediately above the disc 48 andin sliding engagement therewith is a washer t9 which ts snugly in thetop ot' the receptacle 15 below the diaphragm. As the stem 18 swingsabout its pivot on the diaphragm the disc 4:8 slips freely with relationto the washer a9. "llhe disc and the washer form a tight joint, however,and thus prevent the fusible metal trom coming in contact with thediaphragm. 'lhe dise and washer are made of ay suitable material torwhich the fusible metal has no at'linity, such as mica.

While ll have described my invention as embodied in concrete form and asoperating in a specic manner in accordance with the provisions oit thepatent statutes, it should be understood that l do not limit myinvention thereto, since various moditications thereof will suggestthemselves gto those skilled in the art without departing from thespirit of my invention, the scope of which is set forth in the annexedclaims.

What l claim as new and desire to secure by Letters Patent oit theUnited States, is

1. it temperature cut-out tor electric heaters comprising control meansin the circuit ot' said heater biased to open circuit position, arotatable member for securing said control means in closed circuitposition, a holding member for preventing rotation ot said rotatablemember having a pivotal ott-center connection with said rotatablemember, and temperature responsive means normally securing said holdingmember but releasing :it to permit the opening ot ,the heater circuitupon the occurence or a predetermined temperature.,

2. A temperature cut-out :tor electric heat ers comprising control meansin the circuit et said heater biased to one position, temperatureresponsive means, a pivoted member normally secured against pivotalmovement by said temperature responsive means Bild mensen Jbut. releasedupon the occurrence ot a predetermined temperature, a rotatable member,a connection between said rotatable member and said pivoted memberwhereby said rotatable member is normallyy secured against rotation bysaid pivoted member` and a latching connection between said controlmeans and said rotatable member wllereb)Y saidcontrol means is normallyheld by said rotatable member in another position.

3. temperature cut-out `for electric heaters comprisinp7 control meansin the circuit ot' said heater biased to open circuit position. arotatable member, a stem, a universal pivotal support for said stenn'anott-center pivotal connection between said stem and said rotatablemember. and temperature responsi've meansI normally securing said stembut releasing: it to permit the openinpr otl the heater circuit upon theoccurrence of a' predetermined temperature.

a. A temperature cut-out for electric heaters comprising control meansin the circuit of said heater biased to open circuit, position. arotatable member for securing said control means in closed circuitposition. a stem, a pivotal off-center connection between said stem andsaid rotatable member, a flexible diaphragm forming a support for saidstem to which said stein is rigidly secured, said diaphragm flexing topermit pivotal movement of said stem in all directions, and a fusiblemetal for securing said stem whereby said rotatable member is normallyheld against rotation but is released to permit the opening of theheater circuit upon the fusing of said metal.

5. A temperature eut-out forelectric heaters comprising' control meansin the circuit or said heater biased to open circuit position. a ratchetwheel for securing said control meansin closed circuit position, a stemhavingr an off-center pivotal connection at one end with said ratchetwheel, and a fusible material for securing said stem whereby saidratchet Wheel is normally held against rotation, butl is released topermit the opening of the heater circuit upon the fusing et said metal.

G. A temperature cut-out for electric heaters comprisingr control meansin the circuit ot' said heater biased to open position, a receptacle'. aflexible cover for said receptacle. a siem secured to said cover andextendiner into said receptacle, said stem being pivotally movable, bythe tlexing,r of said cover. a fusible metal in said receptacle normallysecuringr said lstemr` a ratchet wheel for holding said switch in closedposition, and an olf-center pivotal connection between said stem andsaid ratchet wheel wher'eby said ratchet wheel is normally securedagainst rotation by said stem. but rel ased to ertect the opening ofsaid circuit upon the fusing ot' said metal.

7. A temperature cut-out for electric heaters.l comprisingr controlmeans in the circuit of said heater biased to open circuit position, areceptacle, a flexible cover for said receptacle. tending into saidreceptacle, said stem havin;r universal pivotal movement by the flexingof said cover7 a fusible metal in said receptacle normally securing'said stem, and a connection between said stem and said control meanswhereby said control means is normally held in closed circuit position.

tu. A temperature cut-out for electric heaters; comprisingr controlmeans in the circuit of said heater biased to open circuit position, astem having universal pivotal movement, temperature responsive means forsecuring said stem against pivotal movement, and a connection betweensaid stem and said control means whereby said control means is normallyheld in closed circuit position but released by said temperatureresponsive means upon the occurrence or" a predetermined temperature.

In witness whereof, l have hereunto `set my hand this sixteenth day ofDecember, 1924. l

1WILLS N. VANA'ITA.

a stem secured t0 said cover and ex-

